Decathlon Gross Weight Increase

F

flyinhi

New member
Can anyone tell me if it is legal or what is the process for approval of the heavy aluminum gear on Decathlon's with wood spar wings. I have seen two planes with wood spar wings adverised listing the 150 lb gear upgrade. The factory wants to sell wings and said they THINK you need the metal wings to qualify.
Can anyone clear this up or point me to a knowlegable A&P or shop?
I would think the gear upgrade would qualify for any plane under that type certificate, wood or otherwise, but I am not sure.
Thanks
RT
 
flyinhi said:
The factory wants to sell wings and said they THINK you need the metal wings to qualify.
Click to expand...

The factory also spent the time and money to certify the change, and that GW increase is on the Type Certificate not an STC. Why would someone else know more? :p

That said, before you continue, one thing is not a debate. You must have an AEIO-360-H1A (or -H1B) to consider it.

The matter of debate is the 7-1521 covered wing frame requirement on Service Letter 423 and Flight Manual Supplement. Original certification should have called out revision "G" or later of that print. However, we did not list out any revision, perhaps to avoid confusion or we just plain missed it. Technically, the older revs of that drawing include the late model wood spar wings. Nothing was analyzed or tested for them, but it slipped in by mistake. So, there you have it. The technical answer is "yes with a 180" but the literal answer is "no". Clear as mud.
 
Thanks Jerry,
I agree that the factory spent time and money to certify because they get plenty when you buy the kit, to repay them.
I have an FAA source that said the testing for the increase had nothing to do with the wings. They only tested the gear via a drop test for prop clearance to certify. Given that, your comments and the information I can find, you are probably right. The planes that are advertised with wood spars and the increase gross weight are legal but maybe not? clear as mud!
You would think there would be a better source. The FAA is not sure and tech's at the factor THINK it requires the metal spars? They are not sure either!
Do you know what years used the 7-1535 wing frames or 7-1521 covered wing frames?
I appreciate your comments
RT
 
Well, you could talk to one of the two engineers who actually did the project...me being one of them. :p
Unless it was the FAA project engineer (and I know who it was, and I know he won't remember, :lol: ), your FAA contact doesn't know either.

And yes, other structure was analyzed; in this case load comparison. Testing was indeed not required for wings, etc. However, you need the numbers to show that you do not need to test. In this senario, its not a big deal, but its not true that nothing else was looked at. Also, its sort of insulting and naive to say we did nothing but a drop test. A fair gambit of performance testing and sound testing goes along with any change to the operating weight, even if the airplane is unchanged.

The 7-1535 wing frame is the metal spar wing. That one is clear. 1990 and up production.

The 7-1521 COVERED wing is where the loophole lies. In current revision, it only calls out the 7-1535 frame to be covered. However, if you go back to older revisions (i.e. the 70's) it calls out a later version of the wood wing. 7-1521 revision "B" and older call out wing frame 7-1525. Therefore, technically, it looks like a 1977+ wing would fall in. Which also happens to be the time they intoduced the Super Deacthlon with the 180 HP anyway. Older decathlons will have used a different covered wing frame drawing and will even be excluded from the loophole. (If memory serves me, those would be the non-removable wing tips.)

We basically listed both the frame and the covered part number because we sell the wing frame uncovered as well; and did not want to tie down the owner who did his own STC or PMA covering / painting.
 
A point was brought up to me. The gross weight mod requires a new Flight Manual Supplement and we only issued those to existing metal wing customers who had the needed gear swap.

How did these 'advertised' guys you refer to get their hands on one?

If they dont have the FMS, they are not legal.
 
I have a question along the same lines..... I'm looking at buying a 1979 Super Decathlon that has the Factory Metal Spar Wings. I would like to add the Aluminum Heavy Gear, if I go throught with the purchase.... what is the approx price of the Aluminum gear? How much for just parts, and how much if I had the factory do it?

Thanks,
G. Marsolais
 
All good questions for the Parts dept. just give them a call.
As for labor here, our shop rates are very average and I would expect it to be a half days work if there are not other complications.

Example, we got another late 90's in here with 1k hours on it. They never changed the through-bolt....well by this time is was slightly bent and bent bolts don't like to come out of big beefy bushings...
 
"The gross weight mod requires a new Flight Manual Supplement and we only issued those to existing metal wing customers who had the needed gear swap."

Jerry,

Does this mean us wood spar Super Decathlon owners can get the upgraded gear installed by American Champion and be issued a Flight Manual Supplement?

Aaron
 
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